X-Git-Url: https://wimlib.net/git/?p=wimlib;a=blobdiff_plain;f=include%2Fwimlib%2Flist.h;h=6073c23b8088b317baa31cd7649a5860e25c7790;hp=4ac2d0b414f38e8c99d9161e9a144513256ec7c6;hb=013617d583c028b1741bfc05c22e7a626b394174;hpb=26c7f8bb32e4a32001d409f1693e0df016270ed5

diff --git a/include/wimlib/list.h b/include/wimlib/list.h
index 4ac2d0b4..6073c23b 100644
--- a/include/wimlib/list.h
+++ b/include/wimlib/list.h
@@ -249,6 +249,56 @@ static inline void list_splice_tail(struct list_head *list,
 #define list_entry(ptr, type, member) \
 	container_of(ptr, type, member)
 
+/**
+ * list_first_entry - get the first element from a list
+ * @ptr:	the list head to take the element from.
+ * @type:	the type of the struct this is embedded in.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Note, that list is expected to be not empty.
+ */
+#define list_first_entry(ptr, type, member) \
+	list_entry((ptr)->next, type, member)
+
+/**
+ * list_last_entry - get the last element from a list
+ * @ptr:	the list head to take the element from.
+ * @type:	the type of the struct this is embedded in.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Note, that list is expected to be not empty.
+ */
+#define list_last_entry(ptr, type, member) \
+	list_entry((ptr)->prev, type, member)
+
+/**
+ * list_first_entry_or_null - get the first element from a list
+ * @ptr:	the list head to take the element from.
+ * @type:	the type of the struct this is embedded in.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Note that if the list is empty, it returns NULL.
+ */
+#define list_first_entry_or_null(ptr, type, member) \
+	(!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)
+
+/**
+ * list_next_entry - get the next element in list
+ * @pos:	the type * to cursor
+ * @member:	the name of the list_struct within the struct.
+ */
+#define list_next_entry(pos, member) \
+	list_entry((pos)->member.next, typeof(*(pos)), member)
+
+/**
+ * list_prev_entry - get the prev element in list
+ * @pos:	the type * to cursor
+ * @member:	the name of the list_struct within the struct.
+ */
+#define list_prev_entry(pos, member) \
+	list_entry((pos)->member.prev, typeof(*(pos)), member)
+
+
 /**
  * list_for_each	-	iterate over a list
  * @pos:	the &struct list_head to use as a loop cursor.
@@ -274,9 +324,20 @@ static inline void list_splice_tail(struct list_head *list,
  * @member:	the name of the list_struct within the struct.
  */
 #define list_for_each_entry(pos, head, member)				\
-	for (pos = list_entry((head)->next, typeof(*pos), member);	\
-	     &pos->member != (head); 	\
-	     pos = list_entry(pos->member.next, typeof(*pos), member))
+	for (pos = list_first_entry(head, typeof(*pos), member);	\
+	     &pos->member != (head);					\
+	     pos = list_next_entry(pos, member))
+
+/**
+ * list_for_each_entry_reverse - iterate backwards over list of given type.
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ */
+#define list_for_each_entry_reverse(pos, head, member)			\
+	for (pos = list_last_entry(head, typeof(*pos), member);		\
+	     &pos->member != (head); 					\
+	     pos = list_prev_entry(pos, member))
 
 /**
  * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
@@ -288,7 +349,7 @@ static inline void list_splice_tail(struct list_head *list,
 #define list_for_each_entry_safe(pos, n, head, member)			\
 	for (pos = list_entry((head)->next, typeof(*pos), member),	\
 		n = list_entry(pos->member.next, typeof(*pos), member);	\
-	     &pos->member != (head); 					\
+	     &pos->member != (head);					\
 	     pos = n, n = list_entry(n->member.next, typeof(*n), member))
 
 /*
@@ -383,9 +444,9 @@ static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
  * @head:	the head for your list.
  * @member:	the name of the hlist_node within the struct.
  */
-#define hlist_for_each_entry_safe(tpos, pos, n, head, member) 		 \
+#define hlist_for_each_entry_safe(tpos, pos, n, head, member)		 \
 	for (pos = (head)->first;					 \
-	     pos && ({ n = pos->next; 1; }) && 				 \
+	     pos && ({ n = pos->next; 1; }) &&				 \
 		({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
 	     pos = n)